1. Field of the Invention
The present invention relates to apparatus for detecting and indicating leakage in underwater structures and more particularly, but not by way of limitation, it relates to an improved form of probe detector and transmission system for detecting water leakage at crucial underwater locations, such as weld joints and the like, utilizing time domain reflectometry to continually interrogate for the underwater condition while providing a suitable record at the surface position.
2. Description of the Prior Art
The prior art has utilized various forms of sensor and contact structure for determining the presence of moisture or water at or near leakage prone positions. In particular, U.S. Pat. No. 3,981,181 in the name of Ochiai teaches a method for liquid leakage detection that utilizes separation of two conductors by means of a porous insulation material as disposed beneath a tank type of structure wherein pulse reflection is utilized to measure distance along the tank for purposes of locating the leak. A system of time domain reflectometry (TDR) is utilized to convey electronically the trouble indication and location along a linear layout.
U.S. Pat. No. 4,480,251 to McNaughton et al. is of interest for its disclosure of moisture sensing apparatus that utilizes a helical wrap of moisture detecting tape consisting of parallel, spaced conductors. This device utilizes a moisture detection tape that is helically wound along the full length of a cable linkage to indicate leakage of moisture on selected cables, i.e., main line, branches and interconnections. U.S. Pat. No. 3,424,002 in the name of Johnson is an earlier teaching of the use of time domain reflectometry along an immersed transmission line probe for the purpose of detecting liquid level interfaces. This patent too conveys data by means of time domain reflectometry to display output of liquid levels, particularly a range of organic fluids which separate into distinct interfaces.